1. Field of the Invention
The present invention relates to a tube device which is useful in an apparatus for producing semiconductor devices, liquid crystal display devices, or chemicals, a production line for foods, or the like, and also to a piping system including such a tube device.
2. Description of the Prior Art
In a piping system in an apparatus for producing semiconductor devices, liquid crystal display devices, or chemicals, a production line for foods, or the like, higher integrity is required in accordance with the purpose of the piping system. In a piping system for an apparatus for producing semiconductor devices, for example, the number of cleaning steps in various cleaning apparatuses which provide one solution for a semiconductor wet process goes on increasing as the integration of a semiconductor device is advanced. Therefore, cleanness of a cleaning process is requested to attain higher integrity. Consequently, severer requirements are imposed on the technique for cleanly supplying cleaning liquid containing ultrapure water or chemical to a cleaning apparatus. In the current state of the art, chemical is contaminated in processes of mixing, diluting, and transporting in a chemical supplying system. However, the wafer cleanliness must cope with the sub-quarter micron age. As a chemical supplying system, known is a system of the mass preparation type. In the system, chemical is pumped from a receiving tank to a diluting and mixing tank to be adjusted to a desired composition or concentration, further pumped from a supplying tank through a long-distance pipe to a storage tank in a wet station, and then supplied via a pump and a filter to a cleaning tank (for example, see Japanese Patent Application Laying-Open Nos. 2000-265945 and 11-70328).
An example of various tube devices which can be applied to a piping system of such an apparatus for producing semiconductor devices is a heat exchanger shown in FIGS. 19 and 20. The heat exchanger is configured so that a sufficient sealing property is ensured in a casing 71 through which heat exchange pipes 70 are passed, thereby enabling the casing to withstand an internal pressure of an adequate level. The heat exchanger is structured in the following manner (for example, see Japanese Patent Application Laying-Open No. 10-160362). The body of the casing 71 is formed by a cylindrical shell 72. A plurality of metal fastening members 73 such as tie rods or through-bolts are placed parallel to one another on the outer periphery of the shell 72 so as to elongate in the longitudinal direction of the shell. Then both end portions of each of the metal fastening members 73 are passed through lid members 74 which are placed on the end portions of the shell 72, respectively. Nuts 75 are fastened to external thread portions of the ends of the metal fastening members 73 which project from the lid members 74, so that the interfaces between the ends of the shell 72 and butting faces of the lid members 74 are closely sealed. As a result, the casing 71 is hermetically sealed. Furthermore, O-rings 76 serving as sealing members are interposed between the ends of the shell 72 and the butting faces of the lid members 74 (see Japanese Patent Application Laying-Open No. 10-160362).
In such a chemical supplying system of the mass preparation type, it is recognized as a problem that particles or metal contaminations are produced from various liquid-contacting portions of components of all devices including storage tanks, pipes, joints, pumps, heat exchangers, flow meters, filters, and deaerating modules.
On the other hand, an enhanced cleaning speed in a substrate cleaning apparatus for cleaning a semiconductor wafer or the like causes a problem in that the whole apparatus is increased in size and complicated. Particularly, a piping system which is configured by various devices is placed in a clean room, and hence requested to be miniaturized and made more compact.
In various tube devices, since metal materials are often used, metal contaminations are produced, and the device shape is fixed. Therefore, the piping system has a low degree of freedom in design, a dead space is easily caused in pipes, and the piping system tends to be increased in size. As a result, in such tube devices including machines such as a cleaning apparatuses, reductions in size and cost are limited. Moreover, there is no device having a shape which can flexibly satisfy a request for modifying an existing piping system. Consequently, modification of a piping system is largely restricted in space.
In the heat exchanger (tube device) in which the interfaces between the end portions of the shell 72 and the lid members 74 are sealed by fastening the nuts 75 to the metal fastening members 73 such as tie rods or through-bolts, a large number of components are used for attaining the sealing, and hence the cost and size of the casing structure are increased. In the case where the heat exchanger is installed in a place which is exposed to the sulfuric acid atmosphere or the like, the metal fastening members 73 easily corrode and metal pollution inevitably occurs. Recently, it is therefore highly requested to restrict the use of such metal fastening members in, particularly, the field of semiconductor devices.
In order to avoid loosing of the metal fastening members 73, it is necessary to periodically refasten the metal fastening members 73. However, the metal fastening members 73 are generally used in a plural or at least four number, and hence the degrees of refastenings of the metal fastening members 73 are easily dispersed. This dispersion may cause the lid members 74 and the shell 72 to be deformed. When the lid members 74 or the shell 72 is deformed, twisting or distortion is produced between the end portions of the shell 72 and the lid members 74, thereby causing a problem in that local stress concentration occurs to promote development of creep. Moreover, the center axis of a metal tie rod serving as one of the metal fastening members 73 fails to coincide with that of a metal sheath for the tie rod, and the rod and the sheath rub with each other to cause problems in that the sliding resistance is increased, and that abrasion dust containing metal powder is produced. When the shell 72 or the lid members 74 are deformed, such a component must be replaced with a new one. Usually, these components are formed as machined articles, and therefore relatively expensive. Consequently, the heat exchanger has a configuration where reuse in which a device element (for example, the heat exchange pipes 70) remains to be used also after the casing structure is replaced with a new one is hardly conducted.
In the heat exchanger having the connecting structure in which the O-rings 76 serving as sealing members are interposed between the end portions of the shell 72 and the butting faces of the lid members 74, the corrosion resistance and the service temperature range are restricted by the use of the O-rings 76. For example, chemical of a high temperature cannot be passed through a space which is in contact with the O-rings 76. Furthermore, dust produced from the O-rings 76 may cause a pollution problem. In the recent field of semiconductor devices, therefore, it is highly requested to restrict the use of such O-rings.
In the case where a heat exchanger of this kind is to be used for chemical or the like, the shell 72, the lid members 74, and like components are often made of a fluororesin having excellent corrosion resistance, such as PTFE or PFA. However, a fluororesin has high lubricity, and hence creep due to vibration or heat of a pipe occurs in the connecting portions between the shell 72 and the lid members 74. As a result, there arises a problem in that the metal fastening members 73 such as tie rods or through bolts are loosened and fluid leakage from the connecting portions in the ends of the shell 72 is caused.
Alternatively, thread sealing or welding may be employed as the casing connecting structure between the shell 72 and the lid members 74. However, these measures are not highly effective. In a sealing structure which is based simply on threads, a high sealing property cannot be obtained, the pressure resistance is not sufficiently high, and leakage due to creep easily occurs. Usually, welding requires a skilled technique, and cannot be conducted by an easy work. Therefore, the structure due to welding has problems in that the production efficiency is low, that the on-site workability is poor, and that it is difficult to conduct maintenance and inspection on the site.
The invention has been conducted in order to solve the problems. It is an object of the invention to provide a tube device in which metal members such as a metal fastening member are not used and all components can be made of a synthetic resin, whereby the problems of metal elution and production of metal abrasion powder can be solved, and which is preferably used in an apparatus for producing semiconductor devices, and also a piping system including such a tube device.
It is another object of the invention to provide a tube device which can reduce the sizes of various devices, and miniaturize and compactly form a piping system, and which is preferably used in an apparatus for producing semiconductor devices, and also a piping system including such a tube device.
It is a further object of the invention to provide a tube device in which the number of components, and the production cost can be reduced without using a metal fastening member such as a tie rod or a through-bolt, and an O-ring, which has a casing structure of high pressure resistance, and a sealing structure of high reliability, and which is preferably used in an apparatus for producing semiconductor devices, and also a piping system including such a tube device.
It is a still further object of the invention to provide a tube device which, even when all components are made of a fluororesin, can ensure a high sealing property, and can be applied to and installed in a chemically resistant atmosphere, and also a piping system including such a tube device.